NGC 613 is a barred spiral galaxy in the southern constellation Sculptor. The sum of digits of 613 approximates its visual magnitude.

613 is a mathematical enigma in the bewildering story Number of the End by Jason Earls. "Bring the first digit back to get 136, it's triangular. Now bring the first digit of that back to get 361, it's a square."

6132 is the largest known square that divides a number of
the form n!+1, which happens when n=229, another prime. [Noe]